Classification
621 - Applied physics
205
333 - Economics of land & energy
74
551 - Geology, hydrology & meteorology
70
330 - Economics
36
363 - Other social problems & services
30
620 - Engineering & allied operations
30
624 - Civil engineering
25
660 - Chemical engineering
24
662 - Explosives, fuels & related products
22
600 - Technology
17
549 - Mineralogy
14
550 - Earth sciences
13
338 - Production
10
526 - Mathematical geography
9
553 - Economic geology
9
320 - Political science
8
628 - Sanitary & municipal engineering
8
629 - Other branches of engineering
8
900 - History & geography
8
541 - Physical chemistry
7
000 - Computer science, information & general works
6
380 - Commerce, communications & transportation
6
700 - The arts; fine & decorative arts
6
540 - Chemistry & allied sciences
5
577 - Ecology
5
627 - Hydraulic engineering
5
630 - Agriculture & related technologies
5
560 - Paleontology; paleozoology
4
610 - Medicine & health
4
665 - Industrial oils, fats, waxes & gases
4
140 - Specific philosophical schools
3
530 - Physics
3
576 - Genetics & evolution
3
580 - Plants (Botany)
3
003 - Systems
2
344 - Labor, social, education & cultural law
2
414 - Phonology & phonetics
2
500 - Natural sciences & mathematics
2
543 - Analytical chemistry
2
547 - Organic chemistry
2
581 - Specific topics in natural history
2
622 - Mining & related operations
2
658 - General management
2
910 - Geography & travel
2
100 - Philosophy & psychology
1
170 - Ethics
1
300 - Social sciences
1
304 - Factors affecting social behavior
1
332 - Financial economics
1
341 - Law of nations
1
more ...